On 25 Sep 2019, at 17.03, Alex Ha via dovecot <dovecot@dovecot.org> wrote:

Hi all!

I have two dovecot servers with dsync replication over tcp.
Replication works fine except for one user.

# doveadm replicator status
username                                                                                                 priority fast sync full sync success sync failed
customer@example.com                                                                            none     00:00:33  07:03:23  03:22:31     y

If i run dsync manually, i get the following error message:

dsync-local(customer@example.com): Debug: brain M: -- Mailbox renamed, restart sync --
dsync-local(customer@example.com): Error: BUG: Mailbox renaming algorithm got into a potentially infinite loop, aborting
dsync-local(customer@example.com): Error: Mailbox INBOX.Foldername sync: mailbox_rename failed: Invalid mailbox name 'Foldername-temp-1': Missing namespace prefix 'INBOX.'

I've never fixed this because I haven't figured out how to reproduce it. If it happens with you all the time, could you try:

 - Get a copy of both replica sides, e.g. under /tmp/replica1 and /tmp/replica2

 - Make sure dsync still crashes with them, e.g. doveadm -o mail=maildir:/tmp/replica1 sync maildir:/tmp/replica2

 - Delete all mails and dovecot.index* files (but not dovecot.mailbox.log)

 - Make sure dsync still crashes

 - Send me the replicas - they should no longer contain anything sensitive

As for fixing, you could see if deleting dovecot.mailbox.log from both replicas happens to fix this.